Volcanic eruptions can release large amounts of climatically active gases. An emerging view stresses the role of the size and chemical composition of the plume, including its water content, in controlling the climatic effects of an eruption.
Volcanoes and Climate
The year 2016 marks the 200th anniversary of the year without a summer caused by the 1815 Tambora eruption. Today it may be celebrated for its effects on art and literature, but it also resulted in famine and suffering around the globe. While the biggest volcanic eruptions – including large igneous provinces like the Siberian Traps – are known to be linked to climate upheaval and even mass extinctions, emerging work shows that under the right conditions, smaller eruptions or series of eruptions can also affect climate. This collection explores the historical records of climate and ecological change associated with volcanic activity, as well as the factors that control the climate effects of an eruption.
The 1815 eruption of Tambora caused an unusually cold summer in much of Europe in 1816. The extreme weather led to poor harvests and malnutrition, but also demonstrated the capability of humans to adapt and help others in worse conditions.
Recent observed global warming is significantly less than that simulated by climate models. This difference might be explained by some combination of errors in external forcing, model response and internal climate variability.
200 years after the eruption of Mount Tambora, the eruption volume remains poorly known, as is true for other volcanic eruptions over past millennia. We need better records of size and occurrence if we are to predict future large eruptions more accurately.
The rise and fall of civilizations over the past two millennia was set against a backdrop of climate change. High-resolution climate records evince a link between societal change and a period of cooling in the sixth and seventh centuries.
Ted Nield weighs up histories of two momentous volcanic events in Iceland and Indonesia.
Sulphur-rich eruption defies preparations for an ashy blast.
Sea surface temperatures have varied over the past 2,000 years. A synthesis of surface-temperature reconstructions shows ocean surface cooling from ad 1 to 1800, with much of the trend from 800 to 1800 driven by volcanic eruptions.
The role played by volcanic-induced cooling in the recent warming hiatus is not accurately described in the latest phase of the Coupled Model Intercomparison Project. Here, the authors use satellite and aircraft data to investigate the radiative impact of volcanic aerosols in the lowermost stratosphere since the year 2000.
Following large explosive volcanic eruptions, precipitation decreases over much of the globe. An analysis of streamflow records from fifty large rivers reveals statistically significant flow reductions in some regions, but increases in others.
The North Atlantic Oscillation (NAO) is an important source of climate variability in the Northern Hemisphere; here, a model-tested reconstruction of the NAO for the past millennium reveals that positive NAO phases were predominant during the thirteenth and fourteenth centuries, but not during the whole medieval period.
While present in palaeoclimate records, the drivers behind 20-year climate variability are poorly understood. Here, using climate simulations and in situ and palaeo data, the authors present a possible link between volcanic eruptions, Great Salinity Anomalies and the Atlantic overturning circulation.
A state-of-the-art climate model shows that radiative forcing due to anthropogenic and volcanic aerosols explains the variability in sea surface temperature of the North Atlantic between 1950 and 2005.
Instrumental records, proxy data and climate modelling show that multidecadal variability is a dominant feature of North Atlantic sea-surface temperature variations. Simulations with a coupled climate model suggest that the timing of this variability is determined mainly by external forcing, for example from volcanic eruption or solar forcing.
Global mean surface and tropospheric temperatures have shown slower warming since 1998 than found in climate model simulations. A detailed analysis of observations and climate model simulations suggests that the observed influence of volcanic eruptions on tropospheric temperature has been significant, and that the discrepancy between climate simulations and observations is reduced by up to 15% when twenty-first century volcanic eruptions are accounted for in the models.
The role of natural decadal variability in the global warming slowdown has been hinted at, but not quantified. This study looks at decadal average surface temperature anomalies for the 1980s, 1990s and 2000s. The results show that decadal variability is a large contributor to temperature trends, but its influence has decreased, from 47% in the 1980s to 27% in the 2000s, as anthropogenic warming has increased.
Societal upheaval occurred across Eurasia in the sixth and seventh centuries. Tree-ring reconstructions suggest a period of pronounced cooling during this time associated with several volcanic eruptions.
Model and proxy-based estimates of climate cooling from volcanic eruptions have disagreed. Refined simulations and tree-ring time series converge on a total of 0.8 to 1.3 °C of cooling in the Northern Hemisphere from the 1257 and 1815 eruptions.
Ice-core and tree-ring data show that large volcanic eruptions in the tropics and high latitudes were primary drivers of temperature variability in the Northern Hemisphere during the past 2,500 years, firmly implicating such eruptions as catalysts in major sixth-century pandemics, famines, and socioeconomic disruptions.
Accurate forecasting of tropical precipitation is dependent on our understanding of the hydrological cycle. Here, the authors present a speleothem-derived record of Mesoamerican precipitation variability since the 1930s, and show that multi-decadal declines in rainfall coincide with major volcanic eruptions.
Historical aerosol forcing from large volcanic eruptions are reconstructed from sulphate deposition measured in ice cores. This study updates these records by using a more extensive collection of Antarctic ice cores, which provide new records and accurate dating of published records. The results show that prior to the year 1500 the reconstructions were either previously overestimating global aerosol forcing by 20–30% or underestimating it by 20–50%. This has implications for estimates of climate sensitivity.
Palaeoclimate temperature records are dominated by Northern Hemisphere reconstructions. This study introduces a new Southern Hemisphere millennial temperature reconstruction from terrestrial and oceanic proxy records. This highlights the asynchronicity of temperature fluctuations across the two hemispheres, which should be taken into consideration in climate models and projections.
A period of ocean anoxia about 120 million years ago coincided with high temperatures. A reconstruction of CO2 concentrations shows that volcanic outgassing from the Ontong Java Plateau caused CO2 levels to double during the anoxic event.
Flood basalt eruptions have been linked to extinction events. Numerical simulations suggest that the environmental effects of sulphur emissions from these volcanoes would be limited unless the eruptions were frequent and sustained.
Oceanic anoxic events (OAEs) were episodes of widespread marine anoxia during which large amounts of organic carbon were buried on the ocean floor under oxygen-deficient bottom waters, and OAE2 is the most widespread and best defined OAE of the mid-Cretaceous. It is found that that the marine osmium isotope record changes abruptly just at or before the onset of the OAE2 at two distant sites, and it is calculated that over 97 per cent of the total osmium content at both sites is magmatic in origin, indicative of a widespread magmatic pulse at the onset of OAE2.
Volcanic eruptions release a large amount of sulphur dioxide. This is oxidized to sulphate and can then form sulphate aerosol, which can affect the Earth's radiation balance. Here, past volcanic eruptions and atmospheric conditions are investigated by using sulphur and triple oxygen isotope measurements of atmospheric sulphate preserved in the rock record. The results show that seven eruption-related sulphate aerosol deposition events occurred in the mid-Cenozoic era in the northern High Plains of North America.
The extinction at the Triassic/Jurassic boundary is one of the five largest in Earth’s history. Microfossil and organic geochemical analyses link the vegetation turnover in Europe to the release of pollutants and toxic compounds from flood basalt volcanism in the central Atlantic Ocean.